Transflective liquid crystal display having mutually complementary patterned electrode and reflector

ABSTRACT

A transflective liquid crystal display with uniform cell gap configuration throughout the transmissive and the reflective display region is invented. Mutually complementary common electrode pattern and reflector pattern or mutually complementary ITO pixel electrode pattern and reflector pattern produce an electric field in the transmissive display region that has a uniform longitudinal field and an electric field in the reflective display region that is a fringing field. An initially vertically aligned negative dielectric anisotropic nematic liquid crystal material between the electrodes forms a smaller tilt angle with respect to the substrate normal in the reflective display region while a larger tilt angle with respect to the substrate normal in the transmissive display region. Consequently, the ambient incident light experiences smaller phase retardation in the reflective display region while the light from the backlight source experiences larger phase retardation. Since the ambient light passes through the reflective display region twice while the light from the backlight source passes through the transmissive display region only once, by properly designing the electrodes and the reflector width, the light from both ambient light source and backlight source will experience almost the same phase retardation in both reflective and transmissive display regions. As a result, the electro-optical performance curves of both-transmissive display mode and reflective display mode overlap.

This is a Divisional of application Ser. No. 11/110,229 filed Apr. 20,2005 now U.S. Pat. No. 7,339,641.

FIELD OF THE INVENTION

This invention relates to transflective liquid crystal displays and, inparticular, to designing the common electrode and the pixel electrode togenerate a longitudinal electric field in the transmissive displayregion and to generate a fringing field in the reflective displayregion. Therefore, the initially vertically aligned negative dielectricanisotropic nematic liquid crystal molecules will form a smaller tiltangle with respect to the substrate normal in the reflective displayregion and form a larger tilt angle with respect to the substrate normalin the transmissive display region. Consequently, the ambient incidentlight experiences smaller phase retardation in the reflective displayregion while the light from the backlight source experiences largerphase retardation. Since the ambient light passes through the reflectivedisplay region twice while the light from the backlight source passesthrough the transmissive display region only once, by properly designingthe electrodes and the reflector width, the light from both ambientlight source and backlight source will experience almost the same phaseretardation in both reflective and transmissive display regions. As aresult, the electro-optical performance curves of both transmissivedisplay mode and reflective display mode overlap very well.

BACKGROUND AND PRIOR ART

Transmissive liquid crystal display (LCD) is widely used as informationdisplay tools, such as cell phone, personal digital assistant, laptopcomputer and so on. The most commonly used transmissive twisted-nematic(TN) LCD has a 90° TN liquid crystal layer sandwiched between twoperpendicularly rubbed transparent substrates with Indium-Tin-Oxide(ITO), coatings. Two linear polarizers are placed at the outside oftransparent substrates to act as a polarizer and an analyzer whosetransmission directions are either parallel or perpendicular to therubbing direction of the adjacent substrate. In addition, a backlight isput outside of the polarizer as the light source. Without voltage, theincident light becomes linearly polarized after passing through thepolarizer, then follows the twist structure of TN liquid crystal layer,and finally transmits through the analyzer, resulting in a bright state.When the applied voltage exceeds the threshold voltage, the twiststructure of TN liquid crystal layer is broken and the incident linearpolarizer can not follow the liquid crystal twist structure;consequently, the light, in general, becomes elliptically polarized andthe output transmittance decreases. If the applied voltage is highenough, the volume part of the liquid crystal molecules areapproximately aligned perpendicularly to the substrates, except thecrossed residual boundary liquid crystal layers. In this case, theincident linearly polarized light nearly maintains the same polarizationstate after passing through the entire liquid crystal layer, and then isblocked by the analyzer, resulting in a very good dark state. A majordrawback of the transmissive LCD is that its backlight source should beon all the time when the display is in use; therefore, the powerconsumption is relatively high. Another disadvantage is that the imageof transmissive LCD is easily washed out under strong ambient lightconditions, such as outdoor sunlight.

Reflective LCD, on the other hand, has no built-in backlight source.Instead, it utilizes ambient light for reading the displayed images.U.S. Pat. No. 5,933,207 issued to Wu on Aug. 3, 1999 describes areflective LCD comprising a polarizer, a phase compensation film, aliquid crystal layer, and a reflector. Compared to the transmissive LCD,the reflective LCD has advantages including low power consumption, lightweight, and good outdoor readability. However, a reflective LCD relieson ambient light and thus is inapplicable under low light levels or darkambient conditions.

To utilize the advantages, and overcome the disadvantages, of bothtransmissive LCD and reflective LCD, the transflective LCD is used inthe apparatus, method, system, and device of the present invention.Transflective LCD means the apparatus displays an image in transmissivedisplay mode and reflective display mode either independently orsimultaneously. Therefore, such a transflective LCD is designed to beused under any ambient circumstances; U.S. Pat. No. 4,315,258 issued toMcKnight et al on Feb. 9, 1982 proposed a transflective LCD design shownas 10 in FIG. 1. It consists of a front polarizer 11, a LC panel 12, arear polarizer 13, a transflector (partially transmitting mirror) 14 anda backlight source 15. Such a structure is actually modified from theconventional transmissive twisted-nematic (TN) LCD by putting atransflector 14 between the rear polarizer 13 and backlight source 15.This prior art has the advantages of a simple manufacturing process andlow cost; however, it suffers from serious parallax problem because theambient light passes through a very thick glass substrate before it hitsthe transflector. When the display device is viewed from an obliquedirection, the reflected beam and input beam pass through differentpixel areas, resulting in a shadowed image, which is called parallax.Such a parallax problem becomes increasingly serious when the pixel sizedecreases in high resolution display devices.

To overcome the parallax problem, the transflector should be imbedded inthe inner side of the bottom substrate. U.S. Pat. No. 6,281,952 toOkamoto et al proposed a transflective LCD design shown as 200 in FIG.2. It consists of a top linear polarizer 201 a and a bottom linearpolarizer 201 b, a top compensation film 202 a and a bottom compensationfilm 202 b, a top transparent substrate 203 a and a bottom transparentsubstrate 203 b, a liquid crystal layer 208 sandwiched between the topsubstrate 203 a and the bottom substrate 203 b. The top substrate 203 ais coated with a transparent electrode 204 a and a first alignment film205 a. The bottom substrate 203 b is coated with a transflector means212, which contains a non-uniform thickness isolation layer 206, atransparent electrode 204 b and a patterned reflection layer 207. Thereflection layer 207 only covers the thick isolation layer region, whichdefines the reflective display region 210. The thin isolation layerregion, which defines the transmissive region 211, is not covered withthe reflection layer 207. Above the transflector means 212 is a secondalignment film 205 b. The liquid crystal layer 208 contacts with boththe first alignment film 205 a and the second alignment film 205 b. Abacklight source 209 is provided outside of the bottom polarizer 201 bto function as the light source for the transmissive display region 211.Since the transflector means 212 was deposited inside of the bottomsubstrate 203 b, the reflected beam does not pass through the very thickbottom substrate 203 b; therefore, the parallax problem is eliminated.In addition, in order to compensate the optical path difference betweenthe reflective and transmissive display modes, the cell gap intransmissive display region 211 is thicker than that in reflectivedisplay region 210 or the director alignment mechanism in transmissivedisplay region 211 is different from that in reflective display region210. Nevertheless, in either case, the manufacturing process is quitecomplicated and hence the manufacturing cost is relatively high. Anotherdrawback of the different cell gap approach is that the response time inreflective region 210 is different from that in transmissive region 211since the response time is proportional to the square of cell gap.Furthermore, the different cell gap or different alignment fortransmissive and reflective display regions will introduce adisclination line on the border of two regions, which leads to darkstate light leakage and thus degraded contrast ratio of the displayedimage.

To solve the cell gap difference problem while keeping parallax-free intransflective CD, US patent application No. 20030202139 by Choi et aldisclosed a transflective LCD design with partial switching method shownas 300 in FIG. 3. It consists of a top substrate 301 a coated with a toptransparent electrode 302 and an alignment film 303 a, a bottomsubstrate 301 b coated with a transflector means 304 and an alignmentfilm 303 b, and an liquid crystal layer 305 sandwiched between the topsubstrate 301 a and bottom substrate 301 b. The transflector means 304is composed of a non-patterned (continuous) transparent electrode 304 a,a patterned (discontinuous) transparent electrode 304 b, a reflector 304c below the patterned transparent electrode 304 b, and an insulatinglayer 304 d. The non-patterned transparent electrode 304 a area definesthe transmissive display region 306, while the reflector 304 c areadefines the reflective display region 307. The non-patterned transparentelectrode 304 a and the patterned transparent electrode 304 b areconnected with each other and they have the same electric potential. Theelectric field between top transparent electrode 302 and bottomnon-patterned transparent electrode 304 a is strong and almostperpendicular to the substrates 301 a and 301 b. Such a strong electricfield drives the liquid crystal molecules 305 a to almost fully tiltedas shown in FIG. 3. While the electric field between top transparentelectrode 302 and bottom patterned transparent electrode 304 b is afringing field and its overall strength is weaker than the field abovethe non-patterned transparent electrode 304 a. Such a weak fringingfield only drives the liquid crystal molecules 305 b partially tilted.

Therefore, the phase retardation in reflective region is approximatelyhalf of that in transmissive region. However, since the reflector 304 cshould be located under the discontinuous electrode 304 b, theinsulating layer 304 d is inevitable, which increase the manufacturingprocess. To avoid use of an insulating layer 304 d, the discontinuouselectrode 304 b can be coated on the top substrate 301 a. In eithercase, however, the weak electrical field only exists between thediscontinuous electrode gap and the common electrode 302, while theelectrical field right above the discontinuous electrode 304 b is stillas strong as that in transmissive region 306. In other words, not thewhole reflective display region is governed by fringing field.Consequently, the local region liquid crystal molecules above thediscontinuous electrode 304 b are still full-tilted as in transmissiveregion 306. Therefore, the gray scale of reflective and transmissivedisplay modes still does not overlap very well, as shown in FIG. 6 of USpatent application 20030202139.

SUMMARY OF THE INVENTION

A first objective of this invention is to provide a new transflectiveLCD with uniform cell gap throughout the transmissive region andreflective region to simplify the manufacturing process and lower themanufacturing cost.

A second objective of the invention is to provide a new transflectiveLCD with mutually complementary patterned reflector and patterned commonelectrode such that the transmissive display region is governed by alongitudinal electric field, while the reflective display region isgoverned by a fringing field. Therefore, the grayscales of both thereflective mode and the transmissive mode effectively overlap when thepattern size and pattern gap are properly designed.

A third objective of the invention is to provide a new transflective LCDwith uniform alignment treatment in both transmissive and reflectiveregions using mutually complementary reflector pattern and the commonelectrode pattern, which make the electric field in the reflectivedisplay region weaker than that in the transmissive display region toeliminate the disclination line that occurs in the dual cell gap methodof the prior art.

A fourth objective of the invention is to provide a new transflectiveLCD with high contrast ratio and high brightness

A fifth objective of the invention is to provide a new method ofconstructing approximately mutually complementary reflector pattern onthe bottom substrate and common electrode pattern on the top substratein the transflective LCD to ensure that the reflective display region isgoverned by a fringing field while the transmissive display region isgoverned by a longitudinal electric field.

In the reflective display mode, the ambient light travels through thereflective region twice, while in the transmissive display mode, thebacklight passed through transmissive region only once. Thus, there isapproximately twice the difference in the overall optical path betweenthe transmissive and reflective regions. To make a transflective LCDwith uniform cell gap throughout both reflective and transmissiveregions, the phase retardation in reflective region should be half thatof transmissive region at any applied voltage state so that the grayscales of both the reflective mode and transmissive mode can overlapeffectively.

In the apparatus, method, system and device of the present invention, atransflective LCD with a mutually complementary common electrode patternand reflector pattern is disclosed. The transflector is deposited on thebottom substrate and is composed of a non-patterned transparentelectrode coated with patterned reflector. As a result, the area withoutpatterned reflector coverage is transparent, while the area withpatterned reflector coverage is opaque and reflects incident light. Theopaque area defines the reflective display region, while the transparentarea defines the transmissive display region. The non-patternedtransparent electrode can be made of Indium-Tin-Oxide (ITO) and thepatterned reflector is directly deposited above the non-patternedtransparent electrode. The patterned reflector can be made of highreflectivity conductive metal materials, such as aluminum, aluminumalloy, silver, and so on. In addition, the patterned reflector can alsobe fabricated from some nonconductive materials, such as highreflectivity multilayer dielectric thin films. Since the patternedreflector and the non-patterned transparent electrode are connectedtogether, no additional insulating layer is necessary between them. Ifthe patterned reflector is made of conductive metallic materials, thenboth the non-patterned transparent electrode and the patterned reflectorfunction as the pixel electrode. On the other hand, if the patternedreflector is made of nonconductive materials, then only thenon-patterned transparent electrode functions as the pixel electrode.

The top substrate side is coated with a patterned transparent commonelectrode. The common electrode pattern is approximately mutuallycomplementary with the reflector pattern on the bottom substrate. As aresult, there is no common electrode above the reflector coverage, whilethere is common electrode above the transparent pixel electrode areawithout the reflector coverage. Such a mutually complementary reflectorpattern and common electrode pattern configuration ensures that thetransmissive display region is governed by a longitudinal electricfield, while the reflective display region is governed by a fringingfield. Therefore, the electric field in the reflective display region isweaker than that in the transmissive display region. By properlydesigning the pattern size and pattern gap, the single pass phaseretardation in the reflective display region can be approximately halfthe single pass phase retardation in the transmissive display region atany applied voltage state. Because the ambient incident light passesthrough the reflective display region twice while backlight incidentlight passes through the transmissive display region only once, thegrayscales of the reflective display mode effectively overlap those ofthe transmissive display mode.

Further objects and advantages of this invention will be apparent fromthe following detailed description of preferred embodiments which areillustrated schematically in the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic structure of a prior art transflective LCD.

FIG. 2 is a schematic structure of another prior art transflective LCD.

FIG. 3 is a schematic structure of yet another prior art transflectiveLCD.

FIG. 4 is a schematic structure of the transflective LCD in thisinvention according to the first embodiment.

FIG. 5 illustrates the electric field distribution in both thetransmissive display region and reflective display region according tothe first embodiment.

FIG. 6 illustrates the director distribution in both transmissivedisplay region and reflective display region under the electric fielddistribution shown in FIG. 5.

FIG. 7A is a top view of a first example of the mutually complementarycommon electrode pattern on the first substrate and reflector pattern onthe second substrate corresponding to the embodiment shown in FIG. 4.

FIG. 7B shows the oblique view of the first example of the mutuallycomplementary common electrode pattern on the first substrate andreflector pattern on the second substrate corresponding to theembodiment shown in FIG. 4.

FIG. 7C shows the oblique view of a second example of the mutuallycomplementary common electrode pattern on the first substrate andreflector pattern on the second substrate corresponding to theembodiment shown in FIG. 4.

FIG. 7D shows the oblique view of a third example of the mutuallycomplementary common electrode pattern on the first substrate andreflector pattern on the second substrate corresponding to theembodiment shown in FIG. 4.

FIG. 8A is a graph of the voltage dependent reflectance curve of thefirst embodiment of this invention with cell gap d=5 μm and differentreflector width Was shown in FIG. 4.

FIG. 8B is a graph of the voltage dependent transmittance curve of thefirst embodiment of this invention with cell gap d=5 μm and differentreflector width W as shown in FIG. 4.

FIG. 8C is a graphical comparison of the voltage dependent transmittanceand reflectance curves of the first embodiment of this invention withcell gap d=5 μm and the reflector width W=11 μm as shown in FIG. 4.

FIG. 9A is a sectional view of the equilibrium state directordistribution with the strip electrode design of FIG. 7B when rubbingdirection is along x-axis direction.

FIG. 9B is a sectional view of the equilibrium state directordistribution with the strip electrode design of FIG. 7B when rubbingdirection is along y-axis direction.

FIG. 9C is a graph illustrating the rise period dynamic response fordifferent rubbing direction cases in the first embodiment of theinvention.

FIG. 10 shows the schematic structure of the transflective LCD accordingto a second embodiment of the invention.

FIG. 11 shows the electric field distribution in both transmissivedisplay region and reflective display region corresponding to the secondembodiment.

FIG. 12 shows the director distribution in both transmissive displayregion and reflective display region under the electric fielddistribution shown in FIG. 11.

FIG. 13A shows the top view of a first example of the mutuallycomplementary ITO electrode pattern and reflector pattern on the secondsubstrate according to the second embodiment of the present invention.

FIG. 13B shows the oblique view of the first example of the mutuallycomplementary ITO electrode pattern and reflector pattern on the secondsubstrate according to the second embodiment.

FIG. 13C shows the oblique view of a second example of the mutuallycomplementary ITO electrode pattern and reflector pattern on the secondsubstrate according to the second embodiment of the present invention.

FIG. 13D shows the oblique view of a third example of the mutuallycomplementary ITO electrode pattern and reflector pattern on the secondsubstrate in the second embodiment of the present invention.

FIG. 14A is a graph illustrating the voltage dependent reflectance curveof corresponding to the second embodiment of the invention with cell gapd=5 μm and different reflector width W as shown in FIG. 10.

FIG. 14B is a graph illustrating the voltage dependent transmittancecurve of the second embodiment of the invention with cell gap d=5 μm anddifferent reflector width W as shown in FIG. 10.

FIG. 14C is a graphical comparison of the voltage dependenttransmittance and reflectance curves of the second embodiment of theinvention with cell gap d=5 μm and the reflector width W=11 μm as shownin FIG. 10.

FIG. 15A illustrates a section view of the equilibrium state directordistribution with the strip electrode design of FIG. 13B when rubbingdirection is along x-axis direction.

FIG. 15B illustrates a section view of the equilibrium state directordistribution with the strip electrode design of FIG. 13B when rubbingdirection is along y-axis direction.

FIG. 15C is a graph showing the rise period dynamic response fordifferent rubbing direction cases according to the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before explaining the disclosed embodiments of the present invention indetail it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangements shown sincethe invention is capable of other embodiments. Also, the terminologyused herein is for the purpose of description and not of limitation.

The following is a list of the reference numbers used in the drawingsand the detailed specification to identify components:

 10 transflective LCD design (U.S. Pat. No. 4,315,258)  11 frontpolarizer  12 LC panel  13 rear polarizer  14 transflector  15 backlightsource 200 transflective LCD design (U.S. Pat. No. 6,281,952) 201a toplinear polarizer 201b bottom linear polarizer 202a top compensation film202b bottom compensation film 203a top transparent substrate 203b bottomtransparent substrate 204a transparent electrode 204b transparentelectrode 205a first alignment film 205b second alignment film 206isolation layer 207 reflection layer 208 liquid crystal layer 209backlight source 210 reflective display region 211 transmissive displayregion 212 transflector means 300 transflective LCD w/partial switching(U.S. patent application No. 20030202139) 301a top substrate 301b bottomsubstrate 302 transparent electrode 303a alignment film 303b alignmentfilm 304 transflector means 304a non-patterned transparent electrode304b patterned transparent electrode 304c reflector 304d insulatinglayer 305 liquid crystal layer 305a liquid crystal molecules 305b liquidcrystal molecules 306 transmissive region 307 reflective region 400transflective LCD, the first embodiment of the present invention 401afirst polarizer 401b second polarizer 402a first half-wave retardationfilm 402b second half-wave retardation film 403a first quarter-waveretardation film 403b second quarter-wave retardation film 404 negativebirefringence c-film 405a first transparent substrate 405b secondtransparent substrate 406a patterned ITO layer 406b non-patterned ITOlayer 407 patterned reflector 408a first non-conductive planar layer408b second non-conductive planar layer 409a first vertical alignmentfilm 409b second vertical alignment film 410 vertically aligned negativedielectric anisotropic nematic LC layer 411 backlight source 412transmissive display region 413 reflective display region 701 empty area900 transmissive LCD, the second embodiment of the present invention901a first polarizer 901b second polarizer 902a first half-waveretardation film 902b second half-wave retardation film 903a firstquarter-wave retardation film 903b second quarter-wave retardation film904 negative birefringence c-film 905a first transparent substrate 905bsecond transparent substrate 906a non-patterned ITO layer 906b patternedITO layer 907 patterned reflector 908 non-conductive planar layer 909afirst vertical alignment film 909b second vertical alignment film 910vertically aligned negative dielectric anisotropic nematic liquidcrystal layer 911 backlight source 912 transmissive display region 913reflective display region

The apparatus, method, system and device of the present inventiondiscloses a common electrode and pixel electrode design for producing atransflective LCD having a uniform cell gap configuration. In thetransflective LCD, the light from the backlight source passes throughthe liquid crystal layer once in transmissive display region while theambient light passes through the liquid crystal layer twice inreflective display region. Both the backlight source input light and theambient incident light must experience almost the same phase retardationafter passing through liquid crystal layer to achieve overlappinggrayscales of both reflective display mode and transmissive displaymode. To achieve the overlap, the transflective LCD is designed with (1)a mutually complementary common electrode pattern and reflector patternor (2) a mutually complementary transparent pixel electrode pattern andopaque reflector pattern such that the electric field in thetransmissive region is basically longitudinal and substantiallyperpendicular to both top and bottom substrates, while the electricfield in reflective display region is a fringing field, whoselongitudinal component is approximately half the strength of that in thetransmissive display region.

Embodiment 1

FIG. 4 shows the structure of a first embodiment of the transflectiveLCD 400 with uniform cell gap configuration of the present inventionwhich consists of a first transparent substrate 405 a coated with apatterned ITO layer 406 a, a first non-conductive planar layer 408 a,and a first vertical alignment film 409 a; a second transparentsubstrate 405 b coated with a non-patterned ITO layer 406 b, a patternedreflector 407, a second non-conductive planar layer 408 b, and a secondvertical alignment film 409 b; and a vertically aligned negativedielectric anisotropic nematic liquid crystal layer 410 with thickness dsandwiched between the first vertical alignment film 409 a and thesecond vertical alignment film 409 b.

A negative birefringence c-film 404, a first quarter-wave retardationfilm 403 a, a first half-wave retardation film 402 a, and a firstpolarizer 401 a are further laminated on the outer surface of the firstsubstrate 405 a, wherein the negative birefringence c-film 404 contactswith the first substrate 405 a and the first polarizer 401 a faces theobserver. A second quarter-wave retardation film 403 b, a secondhalf-wave retardation film 402 b, and a second polarizer 401 b arelaminated on the outer surface of the second substrate 405 b. Inaddition, a backlight source 411 is further provided outside of thesecond polarizer 401 b. In this configuration, the patterned reflector407 can be made of high reflectivity conductive metal materials, such asaluminum, aluminum alloy, silver and so on. In addition, the patternedreflector 407 can be made of some nonconductive materials, such as highreflectivity multilayer dielectric thin films. In either case, anadditional insulating layer is not required between the patternedreflector 407 and the non-patterned transparent electrode 406 b. If thepatterned reflector 407 is made of conductive metal materials, then bothnon-patterned transparent electrode 406 b and patterned reflector 407function as the pixel electrode and have the same electric potential. Onthe other hand, if the patterned reflector 407 is made of nonconductivematerials, then only the non-patterned transparent electrode 406 bfunctions as the pixel electrode.

The hollow arrows in FIG. 4 represent the propagation directions of bothambient light and backlight source. The non-patterned ITO layer 406 b isfurther connected with the drain electrode of the thin-film transistor(TFT), which is not shown. For purpose of illustration, FIG. 4 onlyshows the basic structure of one pixel area of the whole transflectiveLCD. Other elements, such as the TFT, color filter, storage capacitor,data line, and gate line, although necessary to drive the displaydevice, are not shown. The area of the non-patterned ITO layer 406 bwith patterned reflector 407 coverage is defined as the reflectivedisplay region 413, while the area of the non-patterned ITO layer 406 bwithout patterned reflector 407 coverage is defined as the transmissivedisplay region 412. More importantly, the patterned ITO layer 406 a,which serves as the common electrode, is approximately mutuallycomplementary with the patterned reflector 407. This means that the toppatterned ITO layer 406 a only covers the transmissive display region412 and does not cover the reflective display region 413. Therefore, theelectric field in the transmissive display region 412 is different fromthat in the reflective display region 413.

FIG. 5 shows the electric field distribution in the transmissive displayregion 412 and the reflective display region 413 of one pixel area.Since the top patterned ITO layer 406 a only approximately covers thetransmissive display region 412 and does not cover the reflectivedisplay region 413, the electric field in the transmissive displayregion 412 is a uniform longitudinal field E_(T), which is perpendicularto the first substrate 405 a and the second substrate 405 b. On theother hand, the electric field in the reflective region 413 is afringing field E_(R), which has both longitudinal and horizontalcomponents. Consequently, the longitudinal component of E_(T) in thetransmissive display region 412 is stronger than that of fringing fieldE_(R) in the reflective display region 413. FIG. 6 shows the liquidcrystal director distribution in both the transmissive and reflectivedisplay regions according to the electric field distribution as shown inFIG. 5. Under each applied voltage state, the liquid crystal director inthe transmissive display region 412 is tilted at an angle θ_(T) withrespect to the substrate normal direction, and the liquid crystaldirector in the reflective display region 413 is tilted at an angleθ_(R) with respect to the substrate normal direction. Since thelongitudinal component of E_(T) in the transmissive display region 412is stronger than that of E_(R) in the reflective display region 413 andthe initially vertically aligned negative dielectric anisotropic nematicliquid crystal molecules only respond to the longitudinal component ofthe electric field, the tilt angle θ_(R) in the reflective displayregion 413 is smaller than the tilt angle θ_(T) in the transmissivedisplay region 412. As a result, the phase retardation of liquid crystallayer 410 in the transmissive region 412 is larger than that in thereflective region 413. By properly designing the width W of thereflective display region and the cell gap d, the phase retardation ofliquid crystal layer 410 in the transmissive display region 412 can bemade approximately twice that in the reflective display region 413.Because the ambient incident beam passes through the reflective displayregion 413 twice while the beam from the backlight source passes throughthe transmissive display region 412 only once, these two beamsexperience approximately the same overall phase retardation. As aresult, the grayscales of both transmissive display mode and reflectivedisplay mode approximately overlap each other.

In order that the transmissive display region 412 is governed bylongitudinal electric field while the reflective display region 413 isgoverned by a fringing field, the ITO common electrode pattern on thefirst substrate 405 a should be approximately mutually complementary tothe reflector pattern on the second substrate 405 b. FIG. 7A shows thetop view of a first example of the mutually complementary commonelectrode pattern 406 a and reflector pattern 407. On the firstsubstrate 405 a, one portion of the pixel area is occupied by the ITOelectrode pattern 406 a, while the other portion of the pixel area isleft as an empty area 701 and without ITO electrode coverage. On thesecond substrate 405 b, the whole pixel is covered by a non-patternedITO pixel electrode 406 b, which is further covered by a patternedreflector 407. The area of the reflector pattern 407 on the secondsubstrate 405 b approximately matches with the empty area 701 on thefirst substrate 405 a. Therefore, the ITO pattern 406 a on the firstsubstrate 405 a is approximately mutually complementary with thereflector pattern 407 on the second substrate 405 b. To get a betterunderstanding of the mutually complementary relationship, FIG. 7B showsthe oblique view of the first example of the mutually complementarycommon electrode pattern 406 a on the first substrate 405 a andreflector pattern 407 on the second substrate 405 b. In fact, it is notnecessary for the reflector pattern 407 on the second substrate 405 b toexactly match with the empty area 701 on the first substrate 405 a.Mismatches, overlaps or even gaps can exist between the reflectorpattern 407 on the second substrate 405 b and the ITO pattern 406 a onthe first substrate 405 a.

Besides the comb-shaped ITO electrode 406 a and its complementarystrip-shaped reflector pattern 407 shown in FIGS. 7A and 7B, themutually complementary common electrode 406 a and reflector pattern 407can have other pattern designs. For example, FIG. 7C shows an obliqueview of a second example of the mutually complementary common electrodepattern 406 a and reflector pattern 407, where the common electrodepattern 406 a is cross-shaped and its complementary reflector pattern407 is rectangle-shaped. FIG. 7D shows the oblique view of a thirdexample of the mutually complementary common electrode pattern 406 a andreflector pattern 407, where the common electrode pattern 406 a has manycircular holes and its corresponding complementary circular-shapedreflector pattern 407. In fact, as long as the common electrode pattern406 a and the reflector pattern 407 are approximately mutuallycomplementary with each other, any other mutually complementary commonelectrode pattern 406 a and reflector pattern 407 designs may besubstituted in the present invention.

Based on the design principle described above, the voltage dependenttransmittance and reflectance are calculated in a simulation program. Inthe simulation, the panel structure design of FIG. 4 and the electrodedesign of FIG. 7B are employed. Table 1 is a list of the parameters ofthe liquid crystal mixture, MLC-6680 in this example, used for thesimulation. The liquid crystal pretilt angles on both the firstalignment film 409 a and the second alignment film 409 b are 2° withrespect to the substrate normal and the cell gap d is 5 μm in both thetransmissive display region 412 and the reflective display region 413.The optical axes of the first half-wave film 402 a and the firstquarter-wave film 403 a make 15° and 75° with the transmission axis ofthe first polarizer 401 a, respectively. The transmission axis of thesecond polarizer 401 b is perpendicular to that of the first polarizer401 a. The optical axis of the second half-wave film 402 b isperpendicular to that of the first half-wave film 402 a and the opticalaxis of the second quarter-wave film 403 b is perpendicular to that ofthe first quarter-wave film 403 a. The reflector pattern 407 is made ofaluminum with reflective index n=0.895+i·6.67.

FIGS. 8A and 8B are graphs of the voltage dependent reflectance andtransmittance curves, respectively, corresponding to the schematicstructure shown in FIG. 4 with different reflector width W. In bothreflective and transmissive display modes, the ambient incident angleand the detect angle are 0°. From FIG. 8A, it is clear that, inreflective display mode, when the reflector width W changes from 5 μm to19 μm, the maximum reflectance drops continuously and the on-statevoltage increases gradually. Conversely, in the transmissive displaymode, FIG. 8B shows that the maximum transmittance and on-state voltageare approximately constant. This is because the longitudinal electricfield E_(T) in the transmissive display region 412 is almost unaffectedby the reflector width W; however, the fringing field E_(R) in thereflective display region 413 is mainly affected by the reflector widthW. To design a high image quality transflective LCD, the grayscales ofboth reflective and transmissive display modes are highly preferable tooverlap with each other. The graph in FIG. 8C shows the voltagedependent transmittance and reflectance curves for the first embodimentof the present invention with cell gap d=5 μm and the reflector widthW=11 μm. As shown in FIG. 8C, the grayscales of both reflective andtransmissive display modes approximately overlap. In addition, bothmodes have approximately the same threshold voltage and on-statevoltage. These characteristics make a transflective LCD easy to drive,and more importantly, easy to view.

TABLE 1 The parameters of MLC-6608 liquid crystal mixture K₁₁ 16.7 ×10⁻¹² N K₂₂ 7.0 × 10⁻¹² N K₃₃ 18.1 × 10⁻¹² N ε_(//−) 3.6 ε_(⊥) 7.8 n_(e)1.5606 (at λ = 550 nm) n_(o) 1.4770 (at λ = 550 nm)

The rubbing directions of both the first alignment film 409 a and thesecond alignment film 409 b play important roles on image brightness anddynamic response speed. Given the strip electrode design of FIG. 7B asan example, if the rubbing direction is along x-axis direction, which isperpendicular to the strip direction of the reflector pattern 407, thenthe rise period response speed of both reflective display mode andtransmissive display mode is slow. FIG. 9A shows a section view of theequilibrium state director distribution with the strip electrode designof FIG. 7B when rubbing direction is along x-axis direction. Since thefringing field E_(R) in the reflective display region 413 is weaker thanthe longitudinal electric field E_(T) in the transmissive display region412, the liquid crystal molecules in the transmissive display region 412tilt along x-axis direction first and those in the reflective displayregion 413 are pushed and pressed. Contrarily, the reoriented liquidmolecules in the reflective display region 413 push and press the liquidcrystal molecules in the transmissive display region 412. As a result ofthe interaction, the liquid crystal molecules on the border of thereflective display region 413 and the transmissive display region 412deviate out of the x-z plane. In other words, twist deformationevolution occurs on the border of the reflective display region 413 andthe transmissive display region 412. This twist deformation evolution ofliquid crystal molecules consumes a long time; therefore, its riseperiod dynamic speed is slow. On the other hand, if the rubbingdirection is along y-axis direction, which is parallel to the stripdirection of the reflector pattern 407 as shown in FIG. 7B, then therise period response speed of both reflective display mode andtransmissive mode is relatively fast. FIG. 9B shows the section view ofthe equilibrium state director distribution with the strip electrodedesign of FIG. 7B when the rubbing direction is along y-axis. In thisexample, since the rubbing direction is parallel to the strip directionof the reflector pattern 407, the liquid crystal molecules in both thetransmissive display region 412 and the reflective display region 413reorient in the y-z plane and no twist deformation occurs in the wholepixel area. Therefore, when rubbing direction is along the stripdirection of the reflector pattern 407, the dynamic rise time is muchfaster. For comparison purposes, FIG. 9C shows the dynamic response riseperiod for different rubbing directions. As shown in FIG. 9C, when therubbing direction is along y-axis, which is parallel to the stripdirection of the reflector pattern 407, the response speed is faster andthe brightness is higher. Therefore, for the strip shape reflectorpattern, the rubbing angle is preferably parallel to the strip directionof the reflector pattern.

Second Embodiment

In the first embodiment, the common electrode pattern on the firstsubstrate is mutually complementary with the reflector pattern on thesecond substrate; therefore, the first substrate aligns with the secondsubstrate. To avoid that alignment requirement, FIG. 10 shows theschematic structure according to the second embodiment of thetransflective LCD 000 with uniform cell gap configuration according tothe present invention. The structure in the second embodiment includes afirst transparent substrate 905 a coated with a non-patterned ITO layer906 a and a first vertical alignment film 909 a, a second transparentsubstrate 905 b coated with a patterned ITO layer 906 b, a patternedreflector 907, a non-conductive planar layer 908, and a second verticalalignment film 909 b, a vertically aligned negative dielectricanisotropic nematic liquid crystal layer 910 with thickness d sandwichedbetween the first vertical alignment film 909 a and the second verticalalignment film 909 b. A negative birefringence c-film 904, a firstquarter-wave retardation film 903 a, a first half-wave retardation film902 a, and a first polarizer 901 a are further successively laminatedoutside of the first substrate 905 a, wherein the negative birefringencec-film 904 contacts with the first substrate 905 a and the firstpolarizer 901 a faces the observer. A second quarter-wave retardationfilm 903 b, a second half-wave retardation film 902 b, and a secondpolarizer 901 b are further successively laminated outside of the secondsubstrate 905 b. In addition, a backlight source 911 is further providedoutside of the second polarizer 901 b.

The patterned reflector 907 in the second embodiment may be a highreflectivity conductive metal material, such as aluminum, aluminumalloy, silver and so on. In addition, the patterned reflector 907 may bea nonconductive material, such as a high reflectivity multilayerdielectric thin film. When the patterned reflector 907 is a conductivemetal material, then the patterned transparent electrode 906 b andpatterned reflector 907 are not connected. Therefore, only the patternedtransparent electrode 906 b functions as the pixel electrode. On theother hand, if the patterned reflector 907 is a nonconductive material,then the patterned transparent electrode 906 b and the patternedreflector 907 may be connected however, only the patterned transparentelectrode 906 b functions as the pixel electrode. In the secondembodiment of the present invention, the transparent electrode pattern906 b is approximately mutually complementary with the reflector pattern907. The hollow arrows in FIG. 10 represent the propagation directionsof both the ambient light and the backlight source. As shown in FIG. 10,the patterned ITO layer 906 b is further connected with the drainelectrode of the thin-film transistor (TFT), which is not shown here. Infact, FIG. 10 only shows the basic structure of a single pixel area ofthe transflective LCD. Other elements such as the thin-film transistor(TFT), color filter, storage capacitor, data line and gate line,although necessary to drive the display device, are not shown. The areaof the patterned ITO layer 906 b is defined as the transmissive displayregion 912, while the area of the patterned reflector 907 is defined asthe reflective display region 913. More importantly, the patterned ITOlayer 906 b, which serves as the pixel electrode, is approximatelymutually complementary with the patterned reflector 907. Therefore, theelectric field in the transmissive display region 912 is different fromthat in the reflective display region 913.

FIG. 11 shows the electric field distribution in the transmissivedisplay region 912 and the reflective display region 913 of one pixelarea according to the second embodiment. Since the bottom patterned ITOlayer 906 b only approximately covers the transmissive display region912 and does not cover the reflective display region 913, the electricfield in the transmissive display region 912 is a uniform longitudinalfield E_(T), which is perpendicular to the first substrate 905 a and thesecond substrate 905 b. On the other hand, the electric field in thereflective region 913 is a fringing field E_(R), which has bothlongitudinal and horizontal components. Consequently, the longitudinalcomponent of E_(T) in the transmissive display region 912 is strongerthan that of E_(R) in the reflective display region 913. The schematicdiagram in FIG. 12 shows the liquid crystal director distribution inboth transmissive and reflective display regions corresponding to theelectric field distribution as shown in FIG. 11.

Under each applied voltage state, the liquid crystal director in thetransmissive display region 912 is tilted at a θ_(T) angle with respectto the substrate normal direction, and the liquid crystal director: inthe reflective display region 913 is tilted at a θ_(R) angle withrespect to the substrate normal direction. Since the longitudinalcomponent of E_(T) in the transmissive display region 912 is strongerthan that of E_(R) in the reflective display region 913 and theinitially vertically aligned negative dielectric anisotropic nematicliquid crystal molecules only respond to the longitudinal component ofthe electric field, the tilt angle θ_(R) in the reflective displayregion 913 is smaller than the tilt angle θ_(T) in the transmissivedisplay region 912. As a result, the phase retardation of liquid crystallayer 910 in the transmissive region 912 is larger than that in thereflective region 913. By properly designing the width W of thereflective display region and the cell gap d, the phase retardation ofliquid crystal layer 910 in the transmissive display region 912 can bemade approximately twice the phase retardation of liquid crystal layer910 in the reflective display region 913. Because the ambient incidentbeam passes through the reflective display region 913 twice while thebeam from the backlight source passes through the transmissive displayregion 912 only once, these two beams experience approximately the samephase retardation. As a result, the grayscales of both transmissivedisplay mode and reflective display mode approximately overlap.

The patterned ITO electrode 906 b on the second substrate 905 b shouldbe approximately mutually complementary to the reflector pattern 907 onthe second substrate 905 b so that the transmissive display region 912is governed by longitudinal electric field while the reflective displayregion 913 is governed by a fringing field. FIG. 13A shows the top viewof a first example of the mutually complementary ITO electrode pattern906 b and reflector pattern 907. On the first substrate 905 a, the ITOelectrode 906 a is non-patterned. On the second substrate 905 b, oneportion is covered by a patterned ITO pixel electrode 906 b, while theother portion is covered by a complimentarily patterned reflector 907.The ITO pattern 906 b is approximately mutually complementary with thereflector pattern 907 on the second substrate 905 b. FIG. 13B shows theoblique view of the first example of the mutually complementary ITOelectrode pattern 906 b and reflector pattern 907 on the secondsubstrate 905 b. In fact, the reflector pattern 907 does not need to beexactly complementary with the ITO pattern 906 b on the second substrate905 b. Mismatches and gaps may exist between the reflector pattern 907and the ITO pattern 906 b on the second substrate 905 b.

Besides the comb-shaped ITO electrode 906 b and its complementarystrip-shaped reflector pattern 907 shown in FIGS. 13A and 13B, themutually complementary ITO electrode 906 b and reflector pattern 907 mayhave alternative pattern designs. For example, FIG. 13C shows theoblique view of a second example of mutually complementary ITO electrodepattern 906 b and reflector pattern 907, where the ITO electrode pattern906 b is cross-shaped and its complementary reflector pattern 907 isrectangle-shaped. FIG. 13D shows the oblique view of a third example ofthe mutually complementary ITO electrode pattern 906 b and reflectorpattern 907, where the ITO electrode pattern 906 b has circular holesand its corresponding complementary reflector pattern 907 iscircle-shaped. In fact, as long as the ITO electrode pattern 906 b andthe reflector pattern 907 are approximately mutually complementary witheach other, any other mutually complementary ITO electrode pattern 906 band reflector pattern 907 designs may be substituted in the presentinvention.

Based on the design principle described above, the voltage dependenttransmittance and reflectance were calculated with a simulation program.In the simulation, the panel structure design of FIG. 10 and theelectrode design of FIG. 13B were employed. The liquid crystal mixtureMLC-6608 was used and the parameters of the liquid crystal mixture arelisted in Table 1. The liquid crystal pretilt angles on both the firstalignment film 909 a and the second alignment film 909 b were 2° withrespect to the substrate normal and the cell gap d was 5 μm in bothtransmissive display region 912 and reflective display region 913. Theoptical axes of the first half-wave film 902 a and the firstquarter-wave film 903 a make 15° and 75° with the transmission axis ofthe first polarizer 901 a, respectively. The transmission axis of thesecond polarizer 901 b is perpendicular to that of the first polarizer901 a. The optical axis of the second half-wave film 902 b isperpendicular to that of the first half-wave film 902 a and the opticalaxis of the second quarter-wave film 903 b is perpendicular to that ofthe first quarter-wave film 903 a. The reflector pattern 907 is made ofaluminum with reflective index n=0.895+i-6.67.

FIGS. 14A and 14B demonstrate the voltage dependent reflectance curvesand the voltage dependent transmittance curves, respectively, of thesecond embodiment of FIG. 10 according to the present invention withdifferent reflector widths W. In both reflective and transmissivedisplay modes, the ambient incident angle and the detect angle are 0°.From FIG. 14A, it is clear that, in the reflective display mode, whenthe reflector width W changes from 5 μm to 19 μm, the maximumreflectance drops continuously and the on-state voltage increasesgradually. In contrast, in the transmissive display mode, FIG. 14B showsthat the maximum transmittance and on-state voltage is approximatelyconstant because the longitudinal electric field E_(T) in thetransmissive display region 912 is negligibly affected by the reflectorwidth W. Unlike the transmissive display region 912, the fringing fieldE_(R) in the reflective display region 913 is affected by the reflectorwidth W. Therefore, to produce a high image quality transflective LCD,the grayscales of both reflective and transmissive display modespreferably overlap. FIG. 14C shows the voltage dependent transmittanceand reflectance curves of the second embodiment of this invention withcell gap d=5 μm and the reflector width W=11 μm. From this figure, thegrayscales of both reflective and transmissive display modes overlap. Inaddition, both modes have approximately the same threshold voltage andon-state voltage. These characteristics make the transflective LCD ofthe present invention easy to drive, and more importantly, easy to view.

The rubbing directions of both the first alignment film 909 a and thesecond alignment film 909 b affect the image brightness and dynamicresponse speed. Given the strip electrode design of FIG. 13B as anexample, if the rubbing direction is along x-axis direction, which isperpendicular to the strip direction of the reflector pattern 907, thenthe rise period response speed of both the reflective display mode andthe transmissive display mode are slow. FIG. 15A shows the section viewof the equilibrium state director distribution with the strip electrodedesign of FIG. 13B when rubbing direction is along x-axis direction.Since the fringing field E_(R) in the reflective display region 913 isweaker than the longitudinal electric field E_(T) in the transmissivedisplay region 912, the liquid crystal molecules in the transmissivedisplay region 912 will tilt along the x-axis direction first and thosein the reflective display region 913 are pushed and pressed. Contrarily,the reoriented liquid molecules in the reflective display region 913push and press the liquid molecules in the transmissive display region912. As a result of the interaction, the liquid crystal molecules on theborder of the reflective display region 913 and the transmissive displayregion 912 deviate out of the x-z plane. In other words, a twistdeformation evolution occurs on the border of the reflectivedisplay-region 913 and the transmissive display region 912. This twistdeformation evolution of the liquid crystal molecules occurs over a longtime period; therefore, the rise period dynamic speed is slow. On theother hand, if the rubbing direction is along y-axis direction, which isparallel to the strip direction of the reflector pattern 907 as shown inFIG. 13B, then the rise period response speed of both reflective displaymode and transmissive mode is relatively fast. FIG. 15B shows thesection view of the equilibrium state director distribution with thestrip electrode design of FIG. 13B when rubbing direction is alongy-axis direction. In this case, since the rubbing direction is parallelto the strip direction of the reflector pattern 907, the liquid crystalmolecules in both transmissive display region 912 and reflective displayregion 913 reorient in the y-z plane and no twist deformation occurs inthe pixel area. Therefore, when the rubbing direction is along the stripdirection of the reflector pattern 907, the dynamic rise time is faster.As a comparison, FIG. 15C shows the rise period dynamic response fordifferent rubbing direction cases. As shown in FIG. 15C, when therubbing direction is along y-axis, which is parallel to the stripdirection of the reflector pattern 907, not only the response speed isfaster, but the brightness is increased. Therefore, for the strip shapereflector pattern, the rubbing angle is preferably parallel to the stripdirection of the reflector pattern.

In summary, the apparatus, method, system and device of the presentinvention provides a new transflective LCD design with uniform cell gapconfiguration throughout the transmissive and reflective displayregions. Use of a mutually complementary common electrode pattern andreflector pattern or mutually complementary ITO pixel electrode patternand reflector pattern, produces an electric field in the transmissivedisplay region that is a uniform longitudinal field while the electricfield in the reflective display region is a fringing field. Therefore,the initially vertically aligned negative dielectric anisotropic nematicliquid crystal material forms a smaller tilt angle with respect to thesubstrate normal in the reflective display region and simultaneously alarger tilt angle with respect to the substrate normal in thetransmissive display region. Consequently, the ambient incident lightexperiences a reduced phase retardation in the reflective display regionwhile the light from the backlight source experiences an increased phaseretardation. Since the ambient light passes through the reflectivedisplay region twice while the light from the backlight source onlypasses through the transmissive display region once, by properlydesigning the electrodes and the reflector width, the light from bothambient light source and backlight source experience approximately thesame phase retardation in both reflective and transmissive displayregions. As a result, the electro-optical performance curves of bothtransmissive display mode and reflective display mode overlap.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

1. A transflective liquid crystal display consisting essentially of: afirst substrate having at least a first vertical alignment film and atransparent common electrode layer, wherein said transparent commonelectrode layer is laminated between said vertical alignment film andsaid first substrate on an interior side of the first substrate and anegative birefringence c-film, a first quarter-wave retardation film, afirst half-wave retardation film, and a first polarizer successivelylaminated on an exterior side of the first substrate, wherein thenegative birefringence c-film contacts with the first substrate and thefirst polarizer faces an observer; a second substrate having at least asecond vertical alignment film, a non-conductive layer adjacent to thesecond vertical alignment film, a patterned transparent pixel electrode,and a patterned reflector sandwiched between the non-conductive layerand an interior side of the second substrate and second quarter-waveretardation film, a second half-wave retardation film, and a secondpolarizer successively laminated on an exterior side of the secondsubstrate, wherein said patterned transparent pixel electrode, saidpatterned reflector, and said non-conductive layer are sandwichedbetween said second vertical alignment film and said second substrate,wherein said patterned reflector has a reflector pattern that is anapproximately mutually complementary pattern to said patternedtransparent pixel electrode to form alternating transmissive displayregions and reflective display regions on said second substrate, whereina substantially longitudinal electric field perpendicular to the firstand second substrate is generated in said transmissive display regionsand a substantially fringing field having both longitudinal andhorizontal components is generated in said reflective display regions; aliquid crystal material having a vertically aligned negative dielectricanisotropy sandwiched between said first vertical alignment film andsaid second vertical alignment film forming a liquid crystal layerhaving a single cell gap; and a backlight source provided outside of thesecond polarizer.
 2. The transflective liquid crystal display of claim1, wherein said patterned transparent electrode on said second substratefunctions as a pixel electrode.
 3. A method to produce a transflectiveliquid crystal display device consisting essentially of the steps of:providing a first substrate having a first vertical alignment filmthereon and a second substrate having a second vertical alignment filmon an interior surface of the first and second substrate, respectively;successively laminating a negative birefringence c-film, a firstquarter-wave retardation film, a first half-wave retardation film, and afirst polarizer on an exterior surface of the first substrate;successively laminating a second quarter-wave retardation film, a secondhalf-wave retardation film, and a second polarizer on an exterior sideof the second substrate; providing a liquid crystal material withnegative dielectric anisotropy between said first vertical alignmentfilm and said second vertical alignment film; providing a patternedtransparent electrode said second substrate; providing a non-patternedtransparent electrode said first substrate; providing a patternedreflector on said second substrate, wherein said patterned transparentelectrode pattern and said patterned reflector pattern are approximatelymutually complementary to each other to form alternating transmissiveand reflective display regions so that a substantially longitudinalelectric field is generated in said transmissive display regions and asubstantially fringing field is generated in said reflective displayregions; and providing a non-conductive layer between the alternativepatterned reflector and patterned transparent electrode and the secondalignment film.
 4. The method of claim 3, wherein said patternedtransparent electrode is on said first substrate, further comprising:connecting said patterned reflector on said second substrate to saidnon-patterned transparent electrode on said second substrate so that atleast said non-patterned transparent electrode functions as a pixelelectrode.
 5. The method of claim 3, wherein said patterned transparentelectrode is on said second substrate and only said patternedtransparent electrode functions as a pixel electrode.